Electric discharge tube



March 30, 1937. H. e. BOUMEESTER ELECTRIC DISCHARGE TUBE Filed Oct. 4, 1935 INVENTOR. HUIBERT GERARD BOUMEESTER @444 wzzw ATTORNEY.

Patented Mar. 30, 1937 UNITED STATES PATENT OFFl-E' Application ctober'4, 1935, Serial No. 43,505

In Germany October 4, 1934 V 2 Claims.

The invention relates to electric discharge tubes and more particularly to discharge tubes of high power which serve, for example, for the generation or amplification of electrical oscillations.

5 Between the electrodes of power tubes very high voltages may be set up, and the supporting and current supply members of the electrodes must be mounted at a comparatively great distance from one another. Particular attention must be given to the mounting of the grid relatively to the other electrodes and to the supporting and supply members.

It has been suggested to introduce the cathode lead thru the envelope of the discharge tube in the usual manner by means of a stem and press and to attach the grid to a ring enclosing the stem. This manner of attachment entails the disadvantages of short distances between the supporting and supply members of the grid and the cathode members, resulting in spark-over or electrolysis or dielectric losses which destroy the interjacent insulating material. With these forms of construction there may be produced, even without the material being attacked, leak- 5 age currents which injuriously affect the operation of the tube.

The above mentioned drawbacks may be partly overcome by providing the stem with an outer concentric extension as shown, for example, in

United States Patent 1,718,906, issued June 13,

1929 to Mouromtseff. However, in this construction there arise other drawbacks in that such tubes with very high cathode currents, the oathode supply leads must have very large dimensions and must, therefore, be sealed into a wide bulb. In the last mentioned form of construction in which the stem tube is provided with extensions, the cathode stem has to be first sealed into a cylindrical body and then must this body be secured to the bulb. It is consequently necessary to employ in this case a wider bulb than is required for the form of construction where the grid is clamped directly to the cathode stem. It may be mentioned that with a bulb diameter of 16 cms. there exists an atmospheric pressure of about 200 kgs. which, pressing the sealing-in zone, may crack the glass.

A further drawback of the above described form of construction is that it is not easy to heat, during exhaust, the wires or strips which connect the grid to the leading-out member to the temperature required for creating a satisfactory vacuum.

A tube constructed in accordance with this invention overcomes the mentioned disadvantages in a simple manner. According to this invention the supporting and current supply members of the grid of an electric discharge tube of high power are housed in two or more lateral projections of 'thetube. It is advantageous to construct the discharge tube according to the invention in such manner that it has two lateral tubular projections consisting of glass, quartz or similar material and'is closed by means of a metallic body as, for example, ferro-chromium to which are securedthe supporting and current supply members of the grid.

Tubes constructed according. to the invention provide between the gridand the other electrodes a long insulated path without increasing the diameter of I the bulb. Further, it is easy to deprive the grid supply members within the tube of occluded gases simply. by connecting them to a source ofvoltage.

' Further, the construction according to this in.-

vention is much more solid than with the use of a clamping strip surrounding the stem tube or of extensions provided on the stem tube. At the other end, the grid may be supported by the anode with the aid of insulating material such as quartz.

If a tube according to the invention is employed for short wave purposes, in which event large grid currents are produced, the leadingout members may be connected in parallel. In one embodiment of the invention this parallel connection may be made by connecting the ferrochromium bodies to one another by means of a strip or a tube of metal, for example, an aluminum tube, and by providing said strip or tube with a current supply member. This form of construction, further, may increase the dissipation of heat from the glass-metal joint. The cooling of this joint may be improved by making the grid supporting and supply members which are secured to the ferro-chromium bodies of metallic tubes instead of solid metal. Cooling may be efiected by two small tubes which empty into a hollow extension provided at the end of the obturating body and thru which cooling water is caused to circulate.

The invention will be explained more fully with reference to the accompanying drawing in which Figure 1 represents, by way of example, a tube constructed according to the invention, and Figures 2 and 3 show details of said tube. In Figure 1, numeral l denotes the anode of a discharge tube, which anode forms at the same time part of the envelope wall. This portion of the tube may be artificially cooled in any known The tube portion 2 has two lateral tubular projections 8 and 9 provided at endsmetal bodies in and II of, for example, ferrochromium to which are secured-the current sup- 15 ply and supporting members 12 andlrof-ithe grid, which members may be hollow copper rods.

These rods are connected by means :awips M and I to theside rods of the grid 16.

, As is shown in detail in Figure 2 the pointsat which the ferro-chromium bodies are sealed to" the outer wall may be artificially cooled. For-this purpose two small tubes I and H-Lareled into the interior of the hollow bodies HI and jl I, which cool the sealing joint quite satisfactorily.

Figure 3 shows the manner in which, more particularly if the tube is employed for short wave purposes, the ferro-chromium bodies It) and I! may be connected to one another. The connection is established with the aid of a hollow ring 22 of aluminum which is flattened at both ends 23 and 24 and which is provided at its center with a current supply member 25. v i

It appears from the form of construction shown 35 in Figure 1, that between the current supply 7 members of the electrodes there are provided leakage paths of maximum length without increasing the diameter of the bulb. This becomes ob,- viouswhen the form of construction represented 40 in Figure 1 is compared to the form of construction shown in ,Mouromtsefi, supra.

theglass section opposite the anode seal, a grid in and symmetrically spaced from the anode,

'the sole support and lead-in means for said grid comprising a i plurality of metallic bodies sealed at circumferentially spaced points in the wall of said glass section intermediate the cathode and anode seals, and rigid supporting members, each member being mechanically secured at one end to one of said bodies .and at the otherend to said 7 rid.

2. An electricdischarge tube or the high power type comprising an envelope with a cylindrical anode, an axially extending glass cylinder sealed j gas tight to said anode with lateral projections intermediate the anode-to-glass seal and the outer end of the glass cylinder, said anode containinga cathode and a-grld, a. plurality of sup-;,

porting and current supply members for the grid housed in said glass cylinder, the lateral projections being sealed gas tight at their ends with inwardly extendinggmetallic bodies to the inner ends of which the current supply and support- 7 ing members of the grid are secured, said bodies being short-circuited exteriorly of the envelope by a short conductor. 7

.HUIBERT GERARD BOUMEESTER. 

